System for gathering and loading oil from underwater oil wells



April 22, 1952 R. G. WATTS 2,594,105 SYSTEM FOR GATHERING AND LOADINGOIL FROM UNDERWATER OIL WELLS Filed May 14, 1948 STORAGE RECEIWNG ZHNK Ill

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INVEN TOR. g g Bid 1 A E? ML Q w 3 2 AGEZVT Patented Apr. 22, 1952SYSTEM FOR GATHERING AND LOADING OIL FROM UNDERWATER OIL WELLS RichardG. Watts, Dallas, Tex., assignor, by mesne assignments, to Socony-VacuumOil Company, Incorporated, New York, N. Y., a corporation of' New YorkApplication May 14, 1948, Serial No. 27,084

8 Claims.

This invention relates to the production of oil from underwater oilwells and relates more particularly to the gathering and the loading fortransportation of oil produced from underwater oil wells.

In the operation of oil wells located on dry land, the oil produced fromthe well may be passed directly from the Christmas tree, 1. e., thevalve and pipe arrangement at the top of the bore hole, to storage tanksto await transportation via pipe line or tank cars to an oil refinery.By providing suflicient storage capacity to compensate for fluctuationsin the rate at which the oil may be transported in the pipe lines orloaded on the tank cars, a continuous rate of production of oil from thewell may be maintained which is highly desirable from the standpoints ofinsuring the maximum total recovery of oil from the producing formation,maximum utility of pumps, valves, lines, etc., and stability ofoperation. The same considerations with respect to maintaining uniformrates of production apply to underwater, or off shore, oil wells anduniform rates of production may be maintained from these wells as fromwells located on dry land by providing sufiicient storage capacity tocompensate for fluctuations in the rate at which the oil may betransported to the refinery.

However, in the operation of underwater oil wells, particular problemsof maintaining uniform rates of production arise from the peculiarnature of the location of the wells. Underwater pipe lines leading fromthe well to the shore are diflicult and expensive to lay and other meansof transportation are economically more desirable. Transportation of oilfrom the Well to the shore by means of barges or tankers is economicallyfavorable and to be preferred to pipe lines. However, where barges areemployed, unfavorable weather conditions of high waves and windsfrequently make it impossible to load the barges and therefore make itnecessary to discontinue production or to provide sufficient storagecapacity to handle continuous production for whatever may be the maximumperiod of adverse weather conditions. On the other hand, the provisionof suificient storage capacity by means of conventional tanks positionedabove the water on pilings is extremely costly, leaving little tochoose, from an economic standpoint, between transportation by bargesand transportation by pipe lines.

It is an object of this method to provide an economical method fortransporting oil from underwater oil wells. It is another object of thisinvention to provide a method whereby oil from underwater oil wells maybe economically transported by barges. It is another object of thisinvention to provide a method for gathering and loading oil fromunderwater oil wells. It is another object of this invention to providean economical system for maintaining continuous production fromunderwater oil wells. It is another object of this invention to providean apparatus for gathering and loading oil from underwater oil wells.These and other objects of the invention will become apparent from thefollowing description thereof.

In accordance with the invention, oil from an underwater oil well isgathered from the well and stored in a storage tank positionedsufficiently below the surface of the water to be unaffected by wind andsurface waves, said tank being maintained liquid full at all times, anddrawing off oil from the storage tank to a transport barge as desired.By maintaining the storage tank liquid full at all times with eitheroil, water, or oil and water, and providing sufficient ballast, ifnecessary, the buoyancy effect of the surrounding water is overcome andthe storage tank is thereby maintained in its underwater position. Thestorage tank is provided with an oil inlet line, an oil outlet linesupported at a mooring dolphin, and provision is made to permit water toenter or leave the storage tank.

By providing a storage tank or a plurality of storage tanks positionedbelow the surface of the water, sufficient storage capacity may beobtained to handle production from a well for long periods of adverseweather conditions, when weather conditions and, by proper anchoring,the

storage tank will not be susceptible to movement or drifting byunderwater currents.

The storage tank may be of any suitable type, such as a cylindricaltank. If desired, an oil transport barge, sunk to an underwaterposition, may be utilized as the storage tank. The tank may bepositioned at the bottom of the body of water, where the bottom is hard,or may be permitted to sink into the bottom, where the bottom 3 is soft.If desired, the tank may be positioned intermediate to the bottom andthe surface of the water, although in this case it will be necessary toprovide anchoring means to provent the tank from rising to the surfacewhere its overall specific gravity is less than that of the surroundingwater, as where it is filled with oil, or hanging means, such as pilingssunk into the bottom, to prevent the tank from sinking to the bottomwhere its over-all specific gravity is greater than the surroundingwater, as where it is filled with water. Ballast may be employed tomaintain the over-all specific gravit of the tank above the specificgravity of the water whereby the tank will maintain its position at thebottom or sunk into the bottom, or prevented from rising if positionedintermediate to the bottom and the surface. Air tanks or the like may beprovided to maintain the over-all specific gravity of the storage tankbelow that of the surrounding water whereby the tank will be preventedfrom sinking where it is positioned intermediate to the bottom and thesurface.

In operation, oil from the well is passed into the storage tank throughthe oil inlet line, at a pressure in excess of the hydrostatic pressureof the surrounding water, and the water contained in the tank displaced.If the pressure of the well is not in excess of the hydrostaticpressure, a pump may be employed to provide the necessary pressure. Thedisplaced water leaves the storage tank through a water line located atthe bottom of the tank and this line is provided with a valve actuatedby change in specific gravity of the liquid passing through to close theline and prevent loss of oil when all the water has been displaced.Preferably, a mechanically operated valve is also provided on the wateroutlet line to insure that no loss of oil is encountered in the event offailure of the specific gravity operated valve. The oil inlet line isprovided with a check valve to prevent any flow of water from thestorage tank to the oil well. The tank is provided with a pressureoperated valve to open if excessive pressures develop within the tank,thereby preventing damage to the tank.

7 Oil is removed from the tank from an oil outlet line, supported by amooring dolphin, to a transport barge. Since water has a higher specificgravity than oil and the oil in the tank is at the hydrostatic pressureof the surrounding water, the oil may flow to the barge without theassistance of pumps, where the tank is at a sufiicient depth. However,the use of a pump is desirable, in any case, in order to lessen the timerequired to load the transport barge; Water enters the tank, therebydisplacing the oil being loaded on the barge, and the water may enterthrough the same line through which it leaves when displaced by the oil,or it may enter through a separate line. The oil outlet line is providedwith a valve, actuated by change in the specific gravity of the liquidpassing through, to close the line and prevent How of Water to thetransport barge when all the oil has been removed from the tank. Where aseparate water inlet line is employed, valve means should be provided toprevent loss of oil from the tank through this line.

Figure 1 is a plan view, schematically illustrating one embodiment ofthe invention. Figure 2 is a plan view, in section, schematicallyillustrating a valve which will permit passage of water but which willclose when oil flows to it.

Figure 3 is a plan view, in section, schematically illustrating a valvewhich will permit passage of oil but which will close when water flowsto it.

Referring now to Figure 1, producing platform i0 is supported on aplurality of pilesll sunk into the bottom 12. Casing I l from oil well15. extends through the water I6 to platform IE] and is capped with theusual arrangement of valves, pipes, and gauges commonly referred to as aChristmas tree and represented here for purposes of simplification asvalve I'I. Line [9 leads from valve [1 to storage receiving tank 20positioned at the bottom of the body of water and carries oil from thewell to the tank. Line I9 is provided with valve 21 which may be anysuitable type of check valve permitting flow of 'fiuid into the tank butpreventing fiow of fiuid from the tank back through line H) to the well.Water in the tank 29 is displaced by the incoming oil and flows from thetank through line 22 to the surrounding water. Line 22 is provided withvalve 24 which permits passage of water but closes when oil begins tofiow through the line.

Details of valve 25 are schematically illustrated in Figure 2. Channel25 leads to the tank and channel 26 leads to line 22. ..Direction offlow from the tank is indicated by the arrows. Ball 2'! has a specificgravity between the specific gravity of oil and water, for example, aspecific gravity of about 0.90 and such specific gravity may be obtainedby hollowing out a suitable volume of the interior of the ball, the holefor hollowing being preferably plugged thereafter to provide a ballhaving a smooth surface. Water flows through the channel 25 and throughperforated cone-shaped disc 29 to channel 26. While water is flowingthrough the valve, the ball, being lighter than the water, will floatand maintain its position in the center of the disc 29. However, whenoil enters the valve, the ball, being heavier than the oil, will sink toits position as shown by dotted lines in throat 30 thereby stopping theflow of oil.

Line 22 is also provided with valve 3i in order to close line 22 in theevent of failure of valve 24 or to prevent water from entering the tankshould it be desired to fill the tank with air to raise it to thesurface or otherwise. Valve 3! is operated by chain 32 connected tosprocket 34 mounted on the platform 10.

Tank 2%} is provided with a liquid level gauge 35 which may be of theelectric resistance'type or other suitable type to indicate the level ofthe oil or water in the tank. Connection 36 leads to indicator 31mounted on platform in whereby the liquid level may be read from theplatform. Tank 20 is also provided with a pressure operated valve 39which opens when the pressure in the tank exceeds a predetermined valuein order to prevent damage to the tank.

Anchor chains 40 and 4| hold the tank between piles 42 and 44. Thepilings 42 and 44 may also serve the purpose of guiding the tank to thesurface where the tank is to be floated for repairs, removal to a newlocation, etc. Two

piles have been shown. However, it may be desirable to employ a largernumber of piles. The piles may be driven such that their tops extendabove the surface of the water as shown, or their tops may be below thesurface of the water.

Oil is removed from tank 28 through line 45 provided with valve 46. Asoil is removed from the tank, water enters through line 22, valve 24permitting fiow of water into the tank. Valve 46 is of the specificgravity operated type and will close to prevent flow of water into line45. Details of valve 46 are schematically illustrated in Figure 3.Channel 4'! leads from the tank and'channel 48 leads to line 45.Direction of flow from the tank is indicated by the arrows. Ball 49 issimilar to ball 21 in valve 24 and will remain in the center ofperforated coneshaped disc 50 while oil flows through the valve. Whenwater fills the valve, ball 49 will float to the position indicated bydotted lines in throat 5| stopping the fiow of water.

Line 45 leads to the surface to mooring dolphin 52 supported on apluraity of piles 54. Preferably, mooring dolphin 52 is located at asufficient distance from producing platform I!) to reduce fire hazardsby preventing spread of any fire from the mooring dolphin to theplatform. Also, the mooring dolphin is located a sufficient distancefrom the producing platform and the piles 42 and 44 to permit loadingbarge 55 to be moored at any position in a circle around the mooringdolphin. Pump 56 assists in removing oil from the tank and may bepowered by a diesel, gas, or gasoline engine or by an electric motor.The oil from pump 56 goes through flexible loading line 51 from swivel58 to barge 55. Buoy 59 supports line 51 at the surface of the water anddrift of the buoy is prevented by anchor line 60 held taut by means ofweight 6|. Valve 62, mechanically operated by chain 54 from sprocket 65,serves the purpose of closing line 45 when barge 55 has been loaded anddisconnected from line 51 in order to prevent any loss of oil from line51 by reason of hydrostatic pressure on the tank 20.

Having thus described my invention it will be understood that suchdescription has been given by way of illustration and example only andnot by way of limitation, reference for the latter purpose being had tothe appended claims.

I claim:

1. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a well head for said well, a storage tankpositioned underwater at a sufficient depth to be unaffected by themoving forces of surface conditions of wind and waves, means for transferring oil from said well head to said storage tank, means associatedwith said last named means for preventing flow of fluid from saidstorage tank to said well head, means for permitting water surroundingsaid storage tank to enter and leave said storage tank, means associatedwith said last named means for permitting said water to enter and leavesaid storage tank but preventing flow of oil therethrough from saidstorage tank, a mooring dolphin, means supported by said mooring dolphinfor transferring oil from said storage tank to a loading vessel, andmeans associated with said last named means for permitting flow of oilfrom said storage tank to a loading vessel but preventing fiow of watertherethrough from said storage tank to a loading vessel.

2. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a well head for said well, a storage tankpositioned underwater at a suflicient depth to be unaffected by themoving forces of surface conditions of wind and waves, means fortransferring oil from said well head to said storage tank, meansassociated with said last named means for preventing flow of fluid fromsaid storage tank to said well head, means for permitting watersurrounding said storage tank to enter and leave said storage tank,means associated with said last named means for permitting said water toenter and leave said storage tank but preventing flow of oiltherethrough from said storage tank, a mooring dolphin, means supportedby said mooring dolphin for transferring oil from said storage tank to aloading vessel, means associated with said means supported by saidmooring dolphin for permitting .fiow of oil from said storage tank to aloading vessel but preventing flow of water therethrough from saidstorage tank to a loading vessel, and valve means associated with saidmeans supported by said mooring dolphin for starting and stopping flowof fluid therethrough.

3. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a well head for said well, a storage tankpositioned underwater at a sufficient depth to be unaffected by themoving forces of surface conditions of wind and waves, means fortransferring oil from said well head to said storage tank, meansassociated with said last named means for preventing fiow of fluid fromsaid storage tank to said well head, means for permitting watersurrounding said storage tank to enter and leave said storage tank,means associated with said last named means for permitting said water toenter and leave said storage tank but preventing flow of oiltherethrough from said storage tank, a mooring dolphin, means fortransferring oil from said storage tank to said mooring dolphin, meansassociated with said last named means for permitting flow of oil fromsaid storage tank to said mooring dolphin but preventing flow of Watertherethrough from said storage tank to said mooring dolphin, and meansfor transferring oil from said mooring dolphin to a loading vessel.

4. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a well head for said oil well, a storagetank positioned underwater at a sufficient depth to be unaffected by themoving forces of surface conditions of wind and waves, an oil transferline connecting said Well head and said storage tank, a check valve insaid oil transfer line to prevent flow of fluid from said storage tankto said well head, a line to said storage tank open to the surroundingwater, a valve in said line permitting flow of Water through said lineto and. from said storage tank but preventing flow of oil through saidline from said storage tank, a mooring dolphin, an oil transfer lineconnected to said storage tank and leading to said mooring dolphin, avalve in said last named oil transfer line permitting flow of oilthrough said line from said storage tank to said mooring dolphin butpreventing fiow of water through said line from said storage tank tosaid mooring dolphin, and a loading line connected at said mooringdolphin to said last named oil transfer line.

5. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a well head for said oil well, a storagetank positioned underwater at a sufficient depth to be unaffected by themoving forces of surface conditions of wind and waves, anchoring meansassociated with said storage tank to prevent drifting of said storagetank by underwater currents, an oil transfer line connecting said wellhead and said storage tank, a check valve in said oil transfer line toprevent flow of fluid from said storage tank to said well head, a lineto said storage tank open to the surrounding water, a valve in said linepermitting flow of Water through said line to and from said storage tankbut preventing flow of oil through said line from said storage tank, amooring dolphin, an oil transfer line connected to said storage tank andleading to said mooring dolphin, a valve in said last named oil transferline permitting flow of oil through said line from said storage tank tosaid mooring dolphin but preventing fiow of water through said line fromsaid storage tank to said mooring dolphin, and a loading line connectedat said mooring dolphin to said last named oil transfer line.

6. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a producing platform set on piles, a wellhead for said oil well on said producing platform, a storage tankpositioned underwater adjacent to said platform and at a sufficientdepth to be unaffected by the moving forces of surface conditions ofWind and Waves, means for transferring oil from said well head to saidstorage tank, means associated with said last named means for preventingflow of fluid from said storage tank to said well head, means forpermitting water surrounding said storage tank to enter and leave saidstorage tank, means associated With said last named means for permittingflow of water to and from said storage tank but preventing flow of oilfrom said storage tank, a mooring dolphin, means for transferring oilfrom said storage tank to said mooring dolphin, means associated withsaid last named means for permitting flow of oil from said storage tankto said mooring dolphin but preventing flow of Water from said storagetank to said mooring dolphin, and means for transferring oil from saidmooring dolphin to a loading vessel.

7. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a producing platform set on piles, a Wellhead for said oil well on said producing platform, a storage tankpositioned underwater adjacent to said platform and at a sufficientdepth to be unaffected by the moving forces of surface conditions ofwind and waves, an oil transfer line connecting said well head and saidstorage tank, a check valve in said oil transfer line to prevent flow offluid from said storage tank to said well head, a line to said storagetank open to the surrounding water, a valve in said line permitting flowof Water through said line to and from said storage tank but preventingflow of oil through said line from said storage tank, a mooring dolphin,an oil transfer line connected to said storage tank and leading to saidmooring dolphin, a valve in said last named oil transfer line permittingflow of oil through said line from said storage tank to said mooringdolphin but preventing flow of water through said line from said storagetank to said mooring dolphin, and a loading line connected atsaidmooring dolphin to said last named oil transfer line.

8. The system for gathering and loading oil from an underwater oil wellwhich comprises in combination a producing platform 'set on piles, aWell head for said oil well on said producing platform, a storage tankpositioned underwater adjacent to said platform and at a suflicientdepth to be unaffected by the moving forces of surface conditions ofwind and waves, anchoring means associated with said storage tank toprevent drifting of said storage tank by underwater currents, an oiltransfer line connecting said well head and said storage tank, a checkvalve in said oil transfer line to prevent flow of fluid from saidstorage tank to said well head, a line to said storage tank open to thesurrounding water, a valve in said line permitting flow of water throughsaid line to and from said storage tank but preventing flow of oilthrough said line from said storage tank, a mooring dolphin, an oiltransfer line connected to said storage tank and leading to said mooringdolphin, a, valve in said last named oil transfer line permitting flowof oil through said line from said storage tank to said mooring dolphinbut preventing flow of Water through said line from said storage tank tosaid mooring dolphin, and a, loading line connected at said mooringdolphin to said last named oil transfer line.

RICHARD G. WATTS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

